CVE-2021-22567Public exploitNetwork attack vector

Code-review bypass via bidirectional Unicode controls

Published Jan 5, 2022 · Updated Apr 21, 2025

Improper access control in Dart SDK before 2.15.0-268.18.beta allows context-dependent attackers to alter program behavior via crafted source code. The compiler interprets Unicode bidirectional controls in string literals by logical code-point order, while editors can render the same line in a misleading visual order; affected analyzers do not flag the discrepancy. Exploitation requires a reviewer to accept attacker-supplied Dart source, after which the compiled program can execute logic that differs from the code's apparent meaning.

CVSS severity4.6
Medium
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper access control in Dart SDK before 2.15.0-268.18.beta allows context-dependent attackers to alter program behavior via crafted source code. The compiler interprets Unicode bidirectional controls in string literals by logical code-point order, while editors can render the same line in a misleading visual order; affected analyzers do not flag the discrepancy. Exploitation requires a reviewer to accept attacker-supplied Dart source, after which the compiled program can execute logic that differs from the code's apparent meaning.

The record

CVE
CVE-2021-22567
Published
Jan 5, 2022
Updated
Apr 21, 2025
Vendor
Go standard library
Product
Dart SDK
Classifications
CWE-284, T1027
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jan 5, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <2.15.0-268.18.beta

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Go standard library · Dart SDKversion=unspecified <2.15.0-268.18.beta

Published CVSS scores

3.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
4.6Google LLCCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-284Improper Access Control
T1027Obfuscated Files or Information

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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